The present invention relates generally to a toner supply device for use in an image forming system, such as a copying machine, a facsimile or a printer. More specifically, the invention relates to a toner supply device for supplying a toner while rotating an exchangeable cylindrical toner cartridge and for breaking local accumulation of the toner in the toner cartridge by rotating the toner cartridge in forward and reverse directions by a predetermined angle during exchange of the cartridge or in a desired situation.
In a typical image forming system, the surface of an electrified photosensitive material drum is electrified, and an image information to be copied is exposed to the surface of the drum to form a latent image. Then, a toner is absorbed into the photosensitive material to form a visible image. This visible image is transferred to the surface of a paper, and the toner is fixed on the surface of the paper by heat and pressure. Then, cleaning and de-electrification are carried out to cause a predetermined image information to be a printed information on the surface of the paper. In a developing process for forming the visible image, the toner, together with a carrier of a magnetic material, is used as a developer.
The carrier serving as a main component included in the developer is used for carrying the toner and producing frictional electrification. Since this carrier is electrified to be used for causing the toner to be absorbed into the photosensitive material drum and the surface of the paper, the carrier does not adhere to the surface of the paper and is not consumed, so that the amount of the carrier does not decrease. On the other hand, although the toner itself is not electrified, the toner is gradually consumed to be decreased when a printed matter is prepared after processes, such as transfer, fixing and cleaning. Therefore, the toner must be supplied as required with the use of the image forming system.
The way for supplying the toner is broadly divided into two methods. One of the methods is a method for providing a cartridge dedicated to the copying machine and for supplying a predetermined amount of toner, which is filled in a container, from a supply port of the cartridge when the residual quantity of the toner in the copying machine is short. According to this method, when the toner is supplied to the cartridge from a container, it is difficult for a usual user to skillfully fill the toner in the small-diameter supply port of the cartridge, if not for experts, so that there is the possibility that the toner spills to dirty user's cloths and/or hands. If the spilled toner is raked up to be put in the cartridge, there is also the possibility that impurities are mixed therein.
The other toner supply method is a method using an exchangeable cartridge. This method is an excellent supply method easy to be used, since the exchangeable cartridge is capable of supplying a toner, which is mixed at the best to cause the image forming system to display the best performance to prepare a copied matter, to the developing part of the image forming system without mixing impurities, and of preventing the user for supplying the toner from spilling the toner or the user's cloths and/or hands from being dirtied.
In order to supply a toner using a conventional toner supply device, an empty cartridge formed so as to have a predetermined shape and standard is detached from a cartridge attaching part of a copying machine, and an exchanged cartridge which has the same shape and standard as those of the empty cartridge and which is filled with a toner, is attached on the cartridge attaching part after being sufficiently shaken. Although there are various shapes and capacities of toner cartridges, there is a cylindrical toner cartridge as one of them. The cylindrical toner cartridge has the merit of being capable of utilizing the inner peripheral wall to efficiently supply a toner to a discharging hole. If the cylindrical cartridge is horizontally arranged, a spiral groove is formed in the inner wall surface of the cylindrical cartridge, or the cylindrical cartridge is rotated about the central axis thereof, so that the toner is guided toward the discharging hole.
However, according to such a conventional toner supply device, it is indicated that the user shall shake the cartridge well before exchange of the cartridge in order to prevent the toner from being locally biased in the cartridge. If the user fails to carry out such a shaking operation, there are some cases where the toner is biased locally in the cartridge. Although the cartridge is exchanged, there is a problem in that the supply of the toner is slow or a desired quantity of supplied toner can not be obtained after exchange of the cartridge.
In addition, according to the above described toner supply device of a type wherein the cylindrical cartridge is rotated, if the power supply of the copying machine is turned off when the cartridge is rotated, the toner discharging hole can not be stopped while facing upwards. Therefore, it is required to provide a mechanism for always detecting the position of the discharging hole when the power supply of the copying machine is turned off regardless of the stop of the copying machine for exchange of the toner cartridge, and for adjusting the stopped position so that the detected discharging hole always faces upwards. Such detecting means or position adjusting mechanism increase the producing costs of the copying machine, so that the user has useless economical loads.